Cholesterol has been implicated by the American Heart Association, the American Medical Association, the Surgeon General and many other medical authorities as a leading cause of heart disease, the number one cause of death in the U.S. More than 64 million Americans are afflicted with heart disease, stroke, or other blood vessel diseases according to the American Heart Association: 1988 Heart Facts. It is well known that the intake of saturated fats causes elevated blood cholesterol in a large segment of the population.
The reduction of saturated fat and cholesterol content in the human diet has thus become an increasingly important goal in modern medicine, especially in view of the preponderance of evidence connecting this component of the diet to increased risk for heart disease, etc. Sixty million Americans, thirty six percent of all adults, need to lower their blood cholesterol because they are at a high risk of coronary disease. (See, e.g., the Jul. 7, 1989 edition of The Journal of the American Medical Association). This is not a problem that affects only adults, however. According to the American Health Foundation, one out of every four children in the U.S. has a cholesterol level that needs to be lowered, and one out of every eight children has a cholesterol level that poses a health risk. The public has become increasing aware of the dangers of cholesterol and saturated fats in their diets.
In addition to the elimination of products containing relatively high levels of saturated fat and cholesterol from the diet, a great deal of attention has been directed to methods of preparing dairy products which have decreased levels of saturated fat and cholesterol.
For example, it is well known that fresh whole cow milk is a desirable food product for human consumption, yet because of its approximately 4 percent milkfat (butterfat) content, it contains high levels of saturated fats and about 30-35 mg cholesterol per 8 oz. serving. The market for fluid milk is enormous. Total milk sales in 1990 in the U.S. were 6.3 Billion Gallons, totaling over $15 Billion Dollars. This is in spite of the fact that milk is in fact, and in the perception of consumers, a leading source of cholesterol in the American diet. Consumers have demonstrated this concern by taking the only action is available to them: a) switching to skim milk or reduced butterfat milk products or b) reducing their total consumption of whole milk.
The development of modified milk products which closely approximate fresh whole milk in taste, body, and appearance, and which are cholesterol-free and have reduced fat content has become increasing important as the above-mentioned alternatives prove to be less than satisfactory. A similar need for the development of other modified dairy products which normally contain butterfat in order to obtain finished dairy products which have reduced fat content and which have lowered cholesterol content or are cholesterol-free, but which closely approximate the unmodified dairy product with respect to taste, texture, mouthfeel, appearance, and total consumption experience is also widely recognized.
It has been possible for some time for dairies to develop a products which are considered to be substantially cholesterol-free. However, removing the cholesterol cost effectively and replicating the taste of whole milk is extremely difficult, and cholesterol-free formulations are constantly introduced which are not satisfactory in this regard.
Milk products having reduced saturated fat content, for example skim milk, are typically prepared by separation of the milkfat from whole milk. The addition of vegetable fat to skim milk produces a milk product generally known as a filled milk product. Skim milk, with or without a vegetable fat additive, may be further processed to make a dried or liquid product.
A dried milk product prepared from skim milk and vegetable fat is described in Howard et. al. U.S. Pat. No. 2,659,676. At least about half of the total fat is palm oil. The product is prepared by heating skim milk to 140.degree. F., adding vegetable fat advantageously with lecithin, pasteurizing at 165.degree. for 15 minutes, homogenizing, and spray drying to produce a dried milk product.
German Offenlegungsschrift 2,444,213 illustrates a dried milk product prepared from a milk of reduced saturated fat content. The milk is evaporated to increase solids concentration, polyunsaturated fat is mixed with the evaporated milk by homogenization, the mixture is optionally re-pasteurized at about 75.degree. to 85.degree. C. until the temperature in the milk tank is uniform, which is said to take about 45 minutes. Thereafter, the mixture is dried to produce a dried milk product. The polyunsaturated fat may include esters of linoleic acid and linolenic acid. The vitamin E-containing product of Example 1 in this reference is claimed to have zero milligrams of cholesterol, and human blood cholesterol levels were said to be decreased.
A canned calcium-enriched milk is described in Bauer U.S. Pat. No. 2,871,123. An edible fat ordinarily is admixed with an emulsifying agent which may be lecithin.
An evaporated milk-like product, prepared directly from powdered skim milk, typically 8 percent vegetable oil and water, is described in Kneeland U.S. Pat. No. 3,011,893. Kneeland heats a mixture of powdered skim milk and water to a temperature of about 120.degree. F., adds vegetable oil, homogenizes, and heat-treats the mixture at 165.degree. to 240.degree. F. (for example at 180.degree. F. for about 5 minutes).
Other filled milk products are described by Bundus U.S. Pat. No. 3,488,198 and Canadian Patent 462,146 (Hauser et. al.).
Bundus describes a filled milk based on the use of a water-in-oil emulsion. His products are said to contain about 0.05-0.5 percent of a water-in-oil emulsifier (rather than a conventional oil-in-water emulsifier); 1-10% fat, and 5-10 percent skim milk solids, the balance being water. The fat is said to be a vegetable fat such as coconut oil, cottonseed oil, palm oil, corn oil, soybean oil, hydrogenated cottonseed oil, hydrogenated soybean oil, peanut oil and olive oil. The filled milk product preferably includes a small amount of cephalin-containing lecithin. Bundus does not suggest that any particular vegetable fats would produce a more beneficial result, and in fact half of his examples use coconut oil, which is frowned upon in low cholesterol diets, as the source of vegetable fat.
The canned, filled milk of the Canadian patent is prepared by vigorously agitating a mixture of skim milk and vegetable oil at a temperature of approximately 210.degree. F. produce an emulsion, and then agitating the mixture under vacuum at a temperature of about 130.degree. F. while introducing vitamins A and D.